import java.util.*;
import java.lang.*;
import java.io.*;

class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
        int m = in.nextInt();
        int n = in.nextInt();
        long[][] a = new long[m][n];
        a[m-1][0] = 1;
        for(int i = m-1; i >= 0; i--) {
            for(int j = 0; j < n; j++) {
                if(i == m-1 && j == 0) continue;
                a[i][j] = (i < m-1 ? a[i+1][j] : 0) + (j > 0 ? a[i][j-1] : 0);
            }
        }
        System.out.print(a[0][n-1]);
	}
}